Impact of anthropogenic activities on the microplastic pollution status of an urbanized wetland

Due to their environmental ubiquity, persistence, and potential effects on living organisms, microplastic pollution has become a global concern. Urban wetlands, catchment basins within cities, are one of the final sinks of these pollutants. We studied the occurrence, abundance, distribution, and physical and chemical characteristics of MPs to determine the impact of anthropogenic activities on the microplastic pollution status in an urbanized wetland. Surface water samples from seven sites inside the urbanized wetland Laguna del Camarón were collected during two climatic seasons (rainy and dry), followed by organic-matter digestion, filtration, microscopic counting and classification by shape and color. Subsequently, the polymers were identified with Fourier-Transform Infrared (FTIR) spectroscopy. MPs concentration was significantly higher in the dry season (2.05 particles/L) than in rainy season (1.17 particles/L), with the higher values occurring in the small inner lagoon (LC6 and LC7), which, according to the Pollution Load Index (PLI), has been considered as unpolluted to moderately polluted and highly polluted with MPs. Fiber shape and black and blue colors are predominant, with polyester (PES), polyethylene (PE), polypropylene (PP), and polystyrene (PS) polymers mainly occurring in this ecosystem consistent with nearby recreational and construction activities. This study revealed spatial and seasonal variations in the MP pollution status, elucidated potential pollution sources, and identified hotspots linked to visitor use and construction activities for targeted intervention (improve onsite waste collection, visitor surveillance, and the placement of bins and informative signs).